Transcript Weather - HRSBSTAFF Home Page

Introduction To Weather
Dynamics
What do you know about weather?
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Key terms?
Why is it important?
How does it affect us?
How does it affect other animals/plants?
Meteorology
The study of
the Earth’s
atmosphere
and weather
systems.
Weather
The day to day
changes in the
atmosphere
at a particular
location
on Earth.
Climate
A
widespread,
long-lasting and
recurring
conditions of the
atmosphere.
Atmosphere
The layer of gases
that surrounds
planet Earth.
The gases are held
in place by
gravity.
Heat and Temperature
• To understand weather and climate we must
understand temperature and heat!
• What happens when you hold a chocolate
bar in your hand?
• THIS IS NOT PART OF THE JOURNAL…
Different ways that heat “moves”
• There are 10 pictures
• For each picture determine the following
answers:
• A) What makes you think that heat is
moving; is there any evidence that you see
showing heat transfer?
• B) Where does the heat come from and
where does it go?
1. Your breath on a cold day
2. Hot chocolate
3. Hot soup in a bowl
4. Geysers in Iceland
This whole area is a geothermal park sitting on top of a huge,
boiling cauldron. Steam and gas escape from the geothermal
system. There are hot springs and mud pots. Mud pots are
often around 70-80’C.
5. Chicks are happy in the winter
until their heat lamp
6. The Desert – heat waves create a
mirage
7. Baking and Cooking
8. Melting Ice Cream
9. Fireplace
10. Boiling Water
Heat can be transferred in
three ways:
1. Conduction
2. Convection
3. Radiation
1. Conduction – the easy definition
Heat is transferred
through a material
without the material
moving.
Only the energy moves.
1. Conduction - complicated
Heat is transferred from one
object to another.
As one molecule is heated it
begins to move and shake
rapidly.
It passes some of its heat
energy to other molecules
around it.
All the molecules of an object
pass heat from one to
another, until they are all
hot.
• http://www.scool.co.uk/gcse/physics/energytransfers/revise-it/how-does-heat-energymove
Conductors
• Solids are the best conductors
• Solids have atoms that are
closer together so the heat is
transferred easier.
• In gases especially the atoms
are too far apart.
Conductors
• Metals are the best conductors.
• Example: Frying pan
• Example: The expansion joint on a
bridge
• Gases are the worst conductors.
• Example: Air
• http://www.wisconline.com/Objects/ViewObject.aspx?ID=SCE304
2. Convection – easy defintion
Transfer of heat
energy through
moving liquids
or gases.
Convection
Hot air rises in cold air.
Hot liquid rises in cold liquid.
2. Convection
Highly energetic
atoms or
molecules
move
from one place to
another.
• When a liquid or gas heats up, the particles
move around more.
• This makes the particles spread out, so they
have more room to move.
• This lowers the density of the substance.
The hotter it gets, the lower the density
goes.
• It is this lower density that makes the hotter
substance rise. The cooler substance has a
higher density, which makes it sink.
Example of Convection
• The heat in a boiling pot of water (steam)
• The heat in a room that rises to the top of
the room
• http://www.wisconline.com/Objects/ViewObject.aspx?ID=S
CE304
3. Radiation
Atoms or molecules
emit
electromagnetic
waves. These waves
carry energy
through space and
deposit it only
when they interact
with some form of
matter.
Examples: Toasters
Sun’s energy (in the
air) that makes us
hotter
Radiation and Colours
• What colours are the best at radiation?
– Black and dull colours
These colours absorb and emit heat.
Poor radiation colours: White and shiny colours.
These colours reflect heat.
Keeping the Heat
• Where is heat lost the most?
• Why?
• Heat energy is transferred from homes by
conduction through the walls, floor, roof and
windows. It is also transferred from homes by
convection. For example, cold air can enter the
house through gaps in doors and windows, and
convection currents can transfer heat energy in the
loft to the roof tiles. Heat energy also leaves the
house by radiation through the walls, roof and
windows.
• http://www.bbc.co.uk/schools/gcsebitesize/s
cience/aqa/energy/heatact.shtml
• Now let’s go back to those pictures and
determine what type of heat transfer is
occurring!
1. Your breath on a cold day
2. Hot chocolate
3. Hot soup in a bowl
4. Geysers in Iceland
This whole area is a geothermal park sitting on top of a huge,
boiling cauldron. Steam and gas escape from the geothermal
system. There are hot springs and mud pots. Mud pots are
often around 70-80’C.
5. Chicks are happy in the winter
until their heat lamp
6. The Desert – heat waves create a
mirage
7. Baking and Cooking
8. Melting Ice Cream
9. Fireplace
10. Boiling Water
Quiz
• 1. What substances can convection happen
in?
– In solids and gases
In solids and liquids
In liquids and gases
• 2. What type of radiation do all hot objects
emit?
– Infra-red radiation
Microwave radiation
Gamma radiation
• 3. What are the best absorbers of thermal
radiation?
– Light, dull surfaces
Black, shiny surfaces
Black, dull surfaces
• 4. What are the worst emitters of thermal
radiation?
– Light, shiny surfaces
Light, dull surfaces
Black, dull surfaces
• 5. How does heat pass through a single pane
of window glass?
– By conduction and convection
By conduction and radiation
By convection and radiation